I think that John's point was that RS232 Serial connectors
are outmoded and generally less and less available as standard
i/o devices on computers (even PCs), despite the fact that USB
may be overkill for this application. This is (or will be when
it is realized), however, a hobbyist project, so RS232 is perfectly
applicable here (and adding the USB logic would be way too
complicated).
I do agree with John on the point that RS232 shouldn't be considered
for a production (read commercial) device.
BTW all USB->RS232 adapters are not equal they fall into several
categories based upon the controller devices they use. Even those
that use the same controller devices can have slightly different
Configuration Descriptors/Device Decriptors/Interface Descriptors/
Endpoint Descriptors causing the software that drives them on the
host to do all sorts of different (and sometimes wacky) things.
--- In
ComputerVoltageSources@yahoogroups.com, "Grant Richter"
<grichter@...> wrote:
>
> I am pretty sure the Renasas part just sets up a standard "tickle
me" for Flash config. During
> power up sequencing it probably blits something out a port pin and
IF it gets a response,
> then switches to a Flash load mode. It was probably designed for
JTAG and they just tacked
> RS-232 level translators on the JTAG pins, and set up the handshake
across RS-232, because
> it was cheaper than a JTAG dongle.
>
> USB is laughably overkill for loading 32K of Flash. But info tech is
SO bloated nowadays they
> need all that bandwidth for the 4 megabytes of handshaking needed to
pass a 32K packet...
>